PORTABLE FOLDING RISER
United States Patent 3747708
A portable folding riser for supporting a choir or the like including a pair of skeletal floor-engaging support frames disposed in spaced parallel upright positions, a plurality of ascending steps having opposite ends pivotally connected to the support frames for collapsing movement of the steps and frames about parallel front-to-rear axes to storage positions with the steps lying in a common plane and the frames lying in a common plane closely parallel to the steps, a brace extending between the support frames to prevent collapsing of the frames relative to the steps, and a plurality of casters on the backs of the support frames for movably supporting the riser on edge when collapsed. An additional tier may be optionally attached to the riser and includes a pair of collapsible frames supporting an additional step at a level above the highest step on the first recited frame.
US Patent References:
Collapsible stand
Ellis - June 1952 - 2598983
Portable bleacher unit
Morford - January 1966 - 3230907
Collapsible stand
Ellis - June 1952 - 2598983
Portable bleacher unit
Morford - January 1966 - 3230907
Inventors:
Wenger, Jerry A. (Owatonna, MN)
Paine, David L. (Ellendale, MN)
Dorschner, Irvin E. (Owatonna, MN)
Paine, David L. (Ellendale, MN)
Dorschner, Irvin E. (Owatonna, MN)
Application Number:
05/200134
Publication Date:
07/24/1973
Filing Date:
11/18/1971
View Patent Images:
Export Citation:
Assignee:
Wenger Corporation (Owatonna, MN)
Primary Class:
Other Classes:
182/179.100, 52/183, 52/9
International Classes:
E04H3/12; E06C1/38; E06C1/397; E04H3/10; E06C1/00; E04H3/12
Field of Search:
52/8,9,10,143 182/159,162,161,178
Primary Examiner:
Machado, Reinaldo P.
Claims:
We claim
1. A folding riser, comprising,
2. A folding riser as defined in claim 1, wherein the support frames are each skeletal and comprise an upright rear leg, an upright front leg, a rigid horizontal crossmember connecting lower ends of the legs, and an inclined brace connecting the rear leg and the crossmember.
3. A folding riser as defined in claim 1, wherein the means pivotally connecting the steps and the support frames comprises a plurality of hinge pins rigidly positioned on each frame beneath each seat, and a hinge plate secured to the adjacent seat with a recess capturing the hinge pin between the plate and the seat.
4. A folding riser as defined in claim 1, wherein the brace comprises a frame pivotable about an upright axis on one support frame and disposed in an upright plane parallel to the rear edge of the upper step.
5. A folding riser as defined in claim 1, wherein the last recited means comprises a spring-biased latch on said other frame for releasably holding said brace in extended position, and cooperating cam means on the brace and the latch for forcing the latch open as the brace is moved to extended position.
6. A folding riser as defined in claim 1, including a stop on said other frame abutting the brace in extended position and a pin securing the brace to the stop.
7. A folding riser as defined in claim 1, including means for releasably holding the brace in collapsed position adjacent said one frame.
8. A folding riser as defined in claim 7, wherein the last recited means comprises a spring-biased latch on the brace for releasably engaging said one frame, and cooperating cam means on said one frame and on the brace for forcing the latch open as the brace is moved to collapsed position.
9. A folding riser as defined in claim 6, wherein the brace comprises a frame pivotable about an upright axis on said one support frame and disposed in an upright plane parallel to the rear edge of the upper step.
10. A portable folding riser, comprising,
11. A portable folding riser as defined in claim 10, wherein the means detachably connecting said other end of the brace to said other frame includes a yieldable latch on said other frame for releasably holding said brace against horizontal pivotal movement on said one frame in a collapsing direction, and means releasably securing the brace to said other frame against vertical movement.
12. A portable folding riser as defined in claim 10, including means for releasably holding the brace in collapsed position on said one frame including a yieldable latch on the brace releasably engaging said one frame.
13. A portable folding riser as defined in claim 10, including means pivotally connecting the steps to the frames comprising a plurality of hinge pins rigidly positioned on each frame beneath each seat, and a hinge plate secured to the adjacent seat with a recess capturing the hinge pin between the plate and the seat.
14. A folding riser, comprising,
15. A folding riser as defined in claim 14, wherein the brace comprises a frame disposed in an upright plane parallel to the rear edge of the upper step, and pivotably mounted at vertically spaced positions on the rear leg of one support frame.
1. A folding riser, comprising,
2. A folding riser as defined in claim 1, wherein the support frames are each skeletal and comprise an upright rear leg, an upright front leg, a rigid horizontal crossmember connecting lower ends of the legs, and an inclined brace connecting the rear leg and the crossmember.
3. A folding riser as defined in claim 1, wherein the means pivotally connecting the steps and the support frames comprises a plurality of hinge pins rigidly positioned on each frame beneath each seat, and a hinge plate secured to the adjacent seat with a recess capturing the hinge pin between the plate and the seat.
4. A folding riser as defined in claim 1, wherein the brace comprises a frame pivotable about an upright axis on one support frame and disposed in an upright plane parallel to the rear edge of the upper step.
5. A folding riser as defined in claim 1, wherein the last recited means comprises a spring-biased latch on said other frame for releasably holding said brace in extended position, and cooperating cam means on the brace and the latch for forcing the latch open as the brace is moved to extended position.
6. A folding riser as defined in claim 1, including a stop on said other frame abutting the brace in extended position and a pin securing the brace to the stop.
7. A folding riser as defined in claim 1, including means for releasably holding the brace in collapsed position adjacent said one frame.
8. A folding riser as defined in claim 7, wherein the last recited means comprises a spring-biased latch on the brace for releasably engaging said one frame, and cooperating cam means on said one frame and on the brace for forcing the latch open as the brace is moved to collapsed position.
9. A folding riser as defined in claim 6, wherein the brace comprises a frame pivotable about an upright axis on said one support frame and disposed in an upright plane parallel to the rear edge of the upper step.
10. A portable folding riser, comprising,
11. A portable folding riser as defined in claim 10, wherein the means detachably connecting said other end of the brace to said other frame includes a yieldable latch on said other frame for releasably holding said brace against horizontal pivotal movement on said one frame in a collapsing direction, and means releasably securing the brace to said other frame against vertical movement.
12. A portable folding riser as defined in claim 10, including means for releasably holding the brace in collapsed position on said one frame including a yieldable latch on the brace releasably engaging said one frame.
13. A portable folding riser as defined in claim 10, including means pivotally connecting the steps to the frames comprising a plurality of hinge pins rigidly positioned on each frame beneath each seat, and a hinge plate secured to the adjacent seat with a recess capturing the hinge pin between the plate and the seat.
14. A folding riser, comprising,
15. A folding riser as defined in claim 14, wherein the brace comprises a frame disposed in an upright plane parallel to the rear edge of the upper step, and pivotably mounted at vertically spaced positions on the rear leg of one support frame.
Description:
BACKGROUND OF THE INVENTION
The present invention relates to a portable folding riser for a choir or the like with a plurality of ascending steps supported on a pair of spaced upright frames which are collapsible to positions wherein the steps lie in a common plane and the support frames lie in a common plane closely parallel to the steps, so that the assembly may be tipped on edge for compact storage against a wall or the like. In the past, there has been some prior work in connection with such structures. For example, U.S. Pat. No. 2,859,488 relates to a folding stand generally of the type described. However, in some instances prior stands have not been entirely portable, and to some extent portability has been restricted by cumbersome construction involving unnecessary complexity and undue weight.
SUMMARY OF THE PRESENT INVENTION
According to the present invention, an improved lightweight readily portable folding riser is constructed with a pair of floor-engaging support frames of skeletal construction, a plurality of steps having opposite ends supported on the frames at ascending levels from front to rear, means pivotally connecting the steps to the frame for collapse, and a collapsible brace of skeletal construction releasably connecting the support frames to prevent collapse.
An important feature of the present invention resides in construction of the brace in the form of a frame pivotable about an upright axis on one of the support frames and disposed in an upright plane parallel to the rear edge of the upper steps so that the brace not only properly spaces the support frames from each other, but also prevents pivotal movement of the support frames relative to the steps, thereby to maintain a rigid structure during use.
In the preferred construction illustrated, the brace has one end releasably secured to the other support frame by means releasably holding the brace against horizontal pivotal movement and by means releasably securing the brace against vertical movement.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a bottom elevational view of a riser incorporating the principles of the present invention, illustrated in collapsed condition and tipped on edge for support by casters which facilitate portability;
FIG. 2 is an end perspective view of the collapsed riser illustrated in FIG. 1, taken from the right end of FIG. 1;
FIG. 3 is a bottom perspective view of the riser illustrated in FIG. 1, shown with the steps, support frames and brace in extended condition preparatory for use but still on edge on the casters for convenient movement;
FIG. 4 is a perspective view of the riser in extended condition and with the legs of the support frames on the floor for use of the riser in the intended manner where a plurality of people may be supported on ascending steps in a front-to-rear direction;
FIG. 5 is a transverse sectional view taken at about the line 5--5 of FIG. 4, and also illustrates in broken line an additional attachable riser tier which may be used with the basic riser;
FIG. 6 is an enlarged fragmentary sectional view taken at about the line 6--6 of FIG. 5;
FIG. 7 is a fragmentary enlarged transverse sectional view taken at about the line 7--7 of FIG. 1, illustrating means for retaining a brace in collapsed storage position closely adjacent to one of the support frames;
FIG. 8 is an enlarged fragmentary plan view of means provided for maintaining the brace in its extended position;
FIG. 9 is a front elevational view partly in section along the line 9--9 of FIG. 8;
FIG. 10 is a side elevational view, partly in section along the line 10--10 of FIG. 9; and
FIG. 11 is a bottom view of the additional riser tier adjacent to the basic riser and illustrating the manner in which the two may be connected.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to the drawings in more detail, a riser embodying the principles of the present invention includes a pair of support frames 10 and 11, and a plurality of steps 12, 13 and 14 supported on the frames 10 and 11 in positions which provide ascending levels when the riser is in extended condition for use in the intended manner with the support frames on the floor as illustrated in FIGS. 4 and 5.
The support frames 10 and 11 are similar in construction for the most part, and similar reference numbers are used in designating the similar components of the two frames. Each frame includes a relatively short front leg 20, a relatively tall rear leg 21, and a crosspiece 22 rigidly connecting the front and rear legs. The frame structure is stabilized by an inclined brace member 24 extending from the top of the rear leg 21 to the crosspiece 22 near the front of the frame. A brace 25 extends from a midportion of the brace 24 to a lower portion of the rear leg 21. In order to provide support for the steps, the inclined brace member 24 includes an intermediate upright leg 27 for the intermediate step 13 and a rear upright leg 28 for the rear step 14.
Each frame includes a separate support for pivotal connection with each of the steps, and each of the supports comprises a fixed hinge pin 30 extending in a front-to-rear direction parallel to the steps adjacent the bottom surface thereof. The hinge pins 30 are all similar, and each includes a long horizontally disposed intermediate portion 30a (FIGS. 5 and 6), a downwardly turned forward end portion 30b and a rearward downwardly turned end portion 30c. The hinge pin for the front step 12 has its forward end portion 30b welded or otherwise secured to the upright front leg 20 of the support frame, and has its rear end portion 30c welded or otherwise secured to the inclined brace 24 of the support frame. The forward end portion 30b of the hinge pin for the intermediate step 13 is welded or otherwise secured to the upright post 27 on the brace 24, and the rearward end 30c of the pin for the intermediate step is welded or otherwise secured to the inclined brace 24. The forward end portion of the hinge pin for the upper step 14 is welded or otherwise secured to the upright post 28 on the inclined brace 24, and the rearward end of the pin for the step 14 is welded or otherwise secured to the inclined brace 24.
It will be understood from the foregoing description that the hinge pins comprise rigid supports on which opposite ends of the steps are supported in order to bear the weight of people on the riser. The hinge pins also facilitate pivotal connection of the steps to the support frames, and to that end, each of the steps has a hinge plate as at 34 secured to the bottom of the step as by screws 35 and formed with a recess receiving the hinge pin 30 and capturing the latter between the hinge plate and the step so that the step and the hinge pin are relatively pivotably movable.
In operation of the riser as thus far described, it will be understood that the hinge pins 30 and the hinge plates 34 pivotally mount the steps 12, 13 and 14 on the support frames 10 and 11 so that the frames and the steps are movable between the collapsed condition illustrated in FIGS. 1 and 2 and the extended condition illustrated in FIGS. 3, 4 and 5. In the collapsed condition illustrated in FIGS. 1 and 2, the steps 12, 13 and 14 lie in a common plane, and the support frames 10 and 11 lie in a common plane closely adjacent to and parallel to the plane containing the steps. In the extended condition of the riser as illustrated in FIGS. 3, 4 and 5, the support frames are disposed in parallel upright planes adjacent opposite ends of the steps and the steps are supported on the frames at ascending levels from front to rear.
In order to maintain the riser in extended condition against collapse while in use, the parallel support frames 10 and 11 are secured against relative movement by means of a brace 40 in the form of a skeletal triangular frame including a horizontally disposed leg 41 and an inclined leg 42. The spaced ends of the legs 41 and 42 are pivotally mounted on U-shaped pivot brackets as at 43 on the upright leg 21 of support frame 10 so that the brace 40 is adapted to pivot on the support frame about an axis parallel to the frame leg 21.
In the collapsed condition of the riser as illustrated in FIG. 1, the brace 40 is adapted to be compactly stored in a plane closely adjacent the support frame 10 and retained in such retracted position by means of a latch device 45 illustrated in FIG. 7. Preferably, the latch device includes an angle-shaped bracket as at 46 welded or otherwise secured to the brace leg 41 and carrying a fixed bolt 47 on which a latch member 48 is loosely mounted. The latch member is yieldably retained in the position illustrated in FIG. 7 by means of a coiled compression spring 50 surrounding the bolt 47 and bearing between the latch member 48 and a head or nut 51 on the bolt 47. The latch member 48 includes an angularly disposed latch portion 53 adapted to catch behind the inclined brace leg 24 on the support frame 10. Additionally, the terminus of the latch portion 53 includes an angularly disposed end portion 55 which functions in cooperation with the brace leg 24 as the brace 40 is moved toward storage position to perform a camming function which laterally deflects the latch member 48 against the yieldable force of the spring 50 so that the latch portion 53 is cammed to one side of the brace leg 24 as the latch portion 53 moved behind the member 24. When it is desired to extend the riser, the latch member 48 may be manually retracted by means of a manually accessible extension 56 in order to release the brace 40.
In order to facilitate handling of the riser in collapsed condition as illustrated in FIGS. 1 and 2, the support frames 10 and 11 are provided with swivel casters as at 57, two mounted on each support frame adjacent the rear leg 21. Each caster 57 includes a rotatable wheel in a yoke which is swivelly mounted on a support bracket 58 secured to the support frame. As seen in FIGS. 2 and 3, each support bracket 58 includes an upright portion 58a secured to the support frame by bolts 59 and a laterally extending flange 58b secured to the caster. The support brackets are secured respectively to opposite sides of the support frame and extend laterally in opposite directions so that the casters are laterally displaced, as viewed in FIG. 2, in order that the collapsed riser will stand by itself.
In order to maintain the riser in extended condition, the free end of the brace 40 is latched in the extended position illustrated in FIG. 3 by means of a latch mechanism 60, illustrated in FIGS. 8, 9 and 10, carried on the rear leg 21 of the support frame 11. The latch mechanism 60 includes an angle-shaped bracket 62 including a flange 63 secured to the rear leg 21 of the support frame 11 and an outwardly turned flange 64 against which the end of the brace leg 41 abuts. As will be understood on reference to the front elevational view of FIG. 8, the flanges 63 and 64 are disposed in vertical planes, and the end of the brace leg 41 abuts the flange 64. In order to retain the brace leg 41 against horizontal pivotal movement about the upright pivot axis of the brace on the support frame 10, a yieldable latch member 65 is utilized.
The latch member 65 is yieldably mounted on a latch support bracket 67 which includes a flange 68 clamped between the flange 63 and the support frame leg 21. The flange 63 and the flange 68 are secured to the leg 21 by means of an appropriate bolt as at 69. A horizontal flange 71 extends laterally from the flange 68 and is formed with upwardly turned tabs as at 72, between which a fixed bolt 74 is mounted. Latch member 65 is loosely mounted on the bolt 75 between the tabs 72 and yieldably maintained in the position illustrated by a coiled compression spring 75 bearing between the latch member 65 and a head or nut 76 on the bolt 74. The latch member 65 includes a flange 78 mounted on the bolt 74 and also includes a latching flange 79 including a latching surface 79 a for retaining the brace leg 41 in position and a camming edge 79b adapted to be engaged by the brace leg 41 during movement of the latter toward the position illustrated in FIGS. 8, 9 and 10 for purposes of laterally displacing the latch member 65 to permit the member 41 to pass the latch and move to the position shown.
The end of the brace leg 41 includes a welded pin as at 80 adapted to register with an aperture as at 81 in the flange 64 for purposes of retaining the member 41 against movement vertically relative to the flange 64.
Referring to FIGS. 5 and 11, an additional tier may be attached to the basic riser described above if it is desired to provide an additional step. As seen best in FIG. 11, the additional tier includes a pair of support frames as at 100 and 101, for supporting a step 103. Frames 100 and 101 are attachable respectively to the frames 10 and 11 in a manner to support the step 103 at a level above the step 14. The support frames 100 and 101 are similar and the components thereof may be designated by similar reference numbers. Each frame includes an upright rear leg 105 and a relatively short front leg 106. The legs 105 and 106 are rigidly connected by a crossmember 107. An additional crossmember 108 extends forwardly from the bottom of the rear leg 105, and the crossmembers 107 and 108 are rigidly connected by an intermediate leg 109. A hinge pin 30 (similar to those previously described) has its front angularly turned end rigidly secured as by welding to the front leg 106 and its rear angularly turned end rigidly secured to the crossmember 107 as by welding. The main intermediate portion of the hinge pin 30 is captured by a hinge plate 34 (similar to those previously described) secured to the seat 103 so that the frames 100 and 101 are pivotally relative to the seat 103.
In order to provide for connection of the frames 100 and 101 to the main riser, the lower end of the front leg 106 of each frame is formed with a reduced terminus as at 112 adapted to fit telescopically into the hollow rectangular upper end of the leg 21, as represented by the broken line 113. Additionally, the forward end of the crossmember 108 is formed with a U-shaped bracket 115 adapted to embrace an intermediate portion of the leg 21. In order to secure the bracket 115 to the leg 21, a bolt of suitable proportions is inserted in an aperture 117 on the bracket 115 to retain the assembly in place. The bolt may be retained in the aperture 117 with a self-locking nut.
In operation, it will be understood that the support frames 100 and 101 of the additional step 103 may be secured to the support frames 10 and 11 of the main riser structure in the manner described above, so that the frames 100 and 101 are pivotally movable with the main frames 10 and 11 between the collapsed and extended positions. in FIG. 5, the additional tier is illustrated in the extended position where the step 103 is disposed at a level above the step 14. On viewing the illustration in FIG. 5, it will be understood that if the additional tier is added to the main riser structure, the casters 57 should be removed from the frames 10 and 11 and mounted in similar positions on frames 100 and 101 in order to facilitate manipulation of the riser in collapsed condition. While the illustration in FIG. 11 has omitted the brace 40 for purposes of simplifying the drawing, it should be understood that the riser with the additional step 103 would also utilize the brace 40 extending between the frames 10 and 11.
The additional riser is disclosed and claimed in the copending application of Harvey M. Urch, et al. Ser. No. 200,115, filed concurrently herewith, Nov. 18, 1971, and assigned to the assignee of this application.
The present invention relates to a portable folding riser for a choir or the like with a plurality of ascending steps supported on a pair of spaced upright frames which are collapsible to positions wherein the steps lie in a common plane and the support frames lie in a common plane closely parallel to the steps, so that the assembly may be tipped on edge for compact storage against a wall or the like. In the past, there has been some prior work in connection with such structures. For example, U.S. Pat. No. 2,859,488 relates to a folding stand generally of the type described. However, in some instances prior stands have not been entirely portable, and to some extent portability has been restricted by cumbersome construction involving unnecessary complexity and undue weight.
SUMMARY OF THE PRESENT INVENTION
According to the present invention, an improved lightweight readily portable folding riser is constructed with a pair of floor-engaging support frames of skeletal construction, a plurality of steps having opposite ends supported on the frames at ascending levels from front to rear, means pivotally connecting the steps to the frame for collapse, and a collapsible brace of skeletal construction releasably connecting the support frames to prevent collapse.
An important feature of the present invention resides in construction of the brace in the form of a frame pivotable about an upright axis on one of the support frames and disposed in an upright plane parallel to the rear edge of the upper steps so that the brace not only properly spaces the support frames from each other, but also prevents pivotal movement of the support frames relative to the steps, thereby to maintain a rigid structure during use.
In the preferred construction illustrated, the brace has one end releasably secured to the other support frame by means releasably holding the brace against horizontal pivotal movement and by means releasably securing the brace against vertical movement.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a bottom elevational view of a riser incorporating the principles of the present invention, illustrated in collapsed condition and tipped on edge for support by casters which facilitate portability;
FIG. 2 is an end perspective view of the collapsed riser illustrated in FIG. 1, taken from the right end of FIG. 1;
FIG. 3 is a bottom perspective view of the riser illustrated in FIG. 1, shown with the steps, support frames and brace in extended condition preparatory for use but still on edge on the casters for convenient movement;
FIG. 4 is a perspective view of the riser in extended condition and with the legs of the support frames on the floor for use of the riser in the intended manner where a plurality of people may be supported on ascending steps in a front-to-rear direction;
FIG. 5 is a transverse sectional view taken at about the line 5--5 of FIG. 4, and also illustrates in broken line an additional attachable riser tier which may be used with the basic riser;
FIG. 6 is an enlarged fragmentary sectional view taken at about the line 6--6 of FIG. 5;
FIG. 7 is a fragmentary enlarged transverse sectional view taken at about the line 7--7 of FIG. 1, illustrating means for retaining a brace in collapsed storage position closely adjacent to one of the support frames;
FIG. 8 is an enlarged fragmentary plan view of means provided for maintaining the brace in its extended position;
FIG. 9 is a front elevational view partly in section along the line 9--9 of FIG. 8;
FIG. 10 is a side elevational view, partly in section along the line 10--10 of FIG. 9; and
FIG. 11 is a bottom view of the additional riser tier adjacent to the basic riser and illustrating the manner in which the two may be connected.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to the drawings in more detail, a riser embodying the principles of the present invention includes a pair of support frames 10 and 11, and a plurality of steps 12, 13 and 14 supported on the frames 10 and 11 in positions which provide ascending levels when the riser is in extended condition for use in the intended manner with the support frames on the floor as illustrated in FIGS. 4 and 5.
The support frames 10 and 11 are similar in construction for the most part, and similar reference numbers are used in designating the similar components of the two frames. Each frame includes a relatively short front leg 20, a relatively tall rear leg 21, and a crosspiece 22 rigidly connecting the front and rear legs. The frame structure is stabilized by an inclined brace member 24 extending from the top of the rear leg 21 to the crosspiece 22 near the front of the frame. A brace 25 extends from a midportion of the brace 24 to a lower portion of the rear leg 21. In order to provide support for the steps, the inclined brace member 24 includes an intermediate upright leg 27 for the intermediate step 13 and a rear upright leg 28 for the rear step 14.
Each frame includes a separate support for pivotal connection with each of the steps, and each of the supports comprises a fixed hinge pin 30 extending in a front-to-rear direction parallel to the steps adjacent the bottom surface thereof. The hinge pins 30 are all similar, and each includes a long horizontally disposed intermediate portion 30a (FIGS. 5 and 6), a downwardly turned forward end portion 30b and a rearward downwardly turned end portion 30c. The hinge pin for the front step 12 has its forward end portion 30b welded or otherwise secured to the upright front leg 20 of the support frame, and has its rear end portion 30c welded or otherwise secured to the inclined brace 24 of the support frame. The forward end portion 30b of the hinge pin for the intermediate step 13 is welded or otherwise secured to the upright post 27 on the brace 24, and the rearward end 30c of the pin for the intermediate step is welded or otherwise secured to the inclined brace 24. The forward end portion of the hinge pin for the upper step 14 is welded or otherwise secured to the upright post 28 on the inclined brace 24, and the rearward end of the pin for the step 14 is welded or otherwise secured to the inclined brace 24.
It will be understood from the foregoing description that the hinge pins comprise rigid supports on which opposite ends of the steps are supported in order to bear the weight of people on the riser. The hinge pins also facilitate pivotal connection of the steps to the support frames, and to that end, each of the steps has a hinge plate as at 34 secured to the bottom of the step as by screws 35 and formed with a recess receiving the hinge pin 30 and capturing the latter between the hinge plate and the step so that the step and the hinge pin are relatively pivotably movable.
In operation of the riser as thus far described, it will be understood that the hinge pins 30 and the hinge plates 34 pivotally mount the steps 12, 13 and 14 on the support frames 10 and 11 so that the frames and the steps are movable between the collapsed condition illustrated in FIGS. 1 and 2 and the extended condition illustrated in FIGS. 3, 4 and 5. In the collapsed condition illustrated in FIGS. 1 and 2, the steps 12, 13 and 14 lie in a common plane, and the support frames 10 and 11 lie in a common plane closely adjacent to and parallel to the plane containing the steps. In the extended condition of the riser as illustrated in FIGS. 3, 4 and 5, the support frames are disposed in parallel upright planes adjacent opposite ends of the steps and the steps are supported on the frames at ascending levels from front to rear.
In order to maintain the riser in extended condition against collapse while in use, the parallel support frames 10 and 11 are secured against relative movement by means of a brace 40 in the form of a skeletal triangular frame including a horizontally disposed leg 41 and an inclined leg 42. The spaced ends of the legs 41 and 42 are pivotally mounted on U-shaped pivot brackets as at 43 on the upright leg 21 of support frame 10 so that the brace 40 is adapted to pivot on the support frame about an axis parallel to the frame leg 21.
In the collapsed condition of the riser as illustrated in FIG. 1, the brace 40 is adapted to be compactly stored in a plane closely adjacent the support frame 10 and retained in such retracted position by means of a latch device 45 illustrated in FIG. 7. Preferably, the latch device includes an angle-shaped bracket as at 46 welded or otherwise secured to the brace leg 41 and carrying a fixed bolt 47 on which a latch member 48 is loosely mounted. The latch member is yieldably retained in the position illustrated in FIG. 7 by means of a coiled compression spring 50 surrounding the bolt 47 and bearing between the latch member 48 and a head or nut 51 on the bolt 47. The latch member 48 includes an angularly disposed latch portion 53 adapted to catch behind the inclined brace leg 24 on the support frame 10. Additionally, the terminus of the latch portion 53 includes an angularly disposed end portion 55 which functions in cooperation with the brace leg 24 as the brace 40 is moved toward storage position to perform a camming function which laterally deflects the latch member 48 against the yieldable force of the spring 50 so that the latch portion 53 is cammed to one side of the brace leg 24 as the latch portion 53 moved behind the member 24. When it is desired to extend the riser, the latch member 48 may be manually retracted by means of a manually accessible extension 56 in order to release the brace 40.
In order to facilitate handling of the riser in collapsed condition as illustrated in FIGS. 1 and 2, the support frames 10 and 11 are provided with swivel casters as at 57, two mounted on each support frame adjacent the rear leg 21. Each caster 57 includes a rotatable wheel in a yoke which is swivelly mounted on a support bracket 58 secured to the support frame. As seen in FIGS. 2 and 3, each support bracket 58 includes an upright portion 58a secured to the support frame by bolts 59 and a laterally extending flange 58b secured to the caster. The support brackets are secured respectively to opposite sides of the support frame and extend laterally in opposite directions so that the casters are laterally displaced, as viewed in FIG. 2, in order that the collapsed riser will stand by itself.
In order to maintain the riser in extended condition, the free end of the brace 40 is latched in the extended position illustrated in FIG. 3 by means of a latch mechanism 60, illustrated in FIGS. 8, 9 and 10, carried on the rear leg 21 of the support frame 11. The latch mechanism 60 includes an angle-shaped bracket 62 including a flange 63 secured to the rear leg 21 of the support frame 11 and an outwardly turned flange 64 against which the end of the brace leg 41 abuts. As will be understood on reference to the front elevational view of FIG. 8, the flanges 63 and 64 are disposed in vertical planes, and the end of the brace leg 41 abuts the flange 64. In order to retain the brace leg 41 against horizontal pivotal movement about the upright pivot axis of the brace on the support frame 10, a yieldable latch member 65 is utilized.
The latch member 65 is yieldably mounted on a latch support bracket 67 which includes a flange 68 clamped between the flange 63 and the support frame leg 21. The flange 63 and the flange 68 are secured to the leg 21 by means of an appropriate bolt as at 69. A horizontal flange 71 extends laterally from the flange 68 and is formed with upwardly turned tabs as at 72, between which a fixed bolt 74 is mounted. Latch member 65 is loosely mounted on the bolt 75 between the tabs 72 and yieldably maintained in the position illustrated by a coiled compression spring 75 bearing between the latch member 65 and a head or nut 76 on the bolt 74. The latch member 65 includes a flange 78 mounted on the bolt 74 and also includes a latching flange 79 including a latching surface 79 a for retaining the brace leg 41 in position and a camming edge 79b adapted to be engaged by the brace leg 41 during movement of the latter toward the position illustrated in FIGS. 8, 9 and 10 for purposes of laterally displacing the latch member 65 to permit the member 41 to pass the latch and move to the position shown.
The end of the brace leg 41 includes a welded pin as at 80 adapted to register with an aperture as at 81 in the flange 64 for purposes of retaining the member 41 against movement vertically relative to the flange 64.
Referring to FIGS. 5 and 11, an additional tier may be attached to the basic riser described above if it is desired to provide an additional step. As seen best in FIG. 11, the additional tier includes a pair of support frames as at 100 and 101, for supporting a step 103. Frames 100 and 101 are attachable respectively to the frames 10 and 11 in a manner to support the step 103 at a level above the step 14. The support frames 100 and 101 are similar and the components thereof may be designated by similar reference numbers. Each frame includes an upright rear leg 105 and a relatively short front leg 106. The legs 105 and 106 are rigidly connected by a crossmember 107. An additional crossmember 108 extends forwardly from the bottom of the rear leg 105, and the crossmembers 107 and 108 are rigidly connected by an intermediate leg 109. A hinge pin 30 (similar to those previously described) has its front angularly turned end rigidly secured as by welding to the front leg 106 and its rear angularly turned end rigidly secured to the crossmember 107 as by welding. The main intermediate portion of the hinge pin 30 is captured by a hinge plate 34 (similar to those previously described) secured to the seat 103 so that the frames 100 and 101 are pivotally relative to the seat 103.
In order to provide for connection of the frames 100 and 101 to the main riser, the lower end of the front leg 106 of each frame is formed with a reduced terminus as at 112 adapted to fit telescopically into the hollow rectangular upper end of the leg 21, as represented by the broken line 113. Additionally, the forward end of the crossmember 108 is formed with a U-shaped bracket 115 adapted to embrace an intermediate portion of the leg 21. In order to secure the bracket 115 to the leg 21, a bolt of suitable proportions is inserted in an aperture 117 on the bracket 115 to retain the assembly in place. The bolt may be retained in the aperture 117 with a self-locking nut.
In operation, it will be understood that the support frames 100 and 101 of the additional step 103 may be secured to the support frames 10 and 11 of the main riser structure in the manner described above, so that the frames 100 and 101 are pivotally movable with the main frames 10 and 11 between the collapsed and extended positions. in FIG. 5, the additional tier is illustrated in the extended position where the step 103 is disposed at a level above the step 14. On viewing the illustration in FIG. 5, it will be understood that if the additional tier is added to the main riser structure, the casters 57 should be removed from the frames 10 and 11 and mounted in similar positions on frames 100 and 101 in order to facilitate manipulation of the riser in collapsed condition. While the illustration in FIG. 11 has omitted the brace 40 for purposes of simplifying the drawing, it should be understood that the riser with the additional step 103 would also utilize the brace 40 extending between the frames 10 and 11.
The additional riser is disclosed and claimed in the copending application of Harvey M. Urch, et al. Ser. No. 200,115, filed concurrently herewith, Nov. 18, 1971, and assigned to the assignee of this application.